Duplex capstan



June 28, 1966 Filed Dec. 31, 1965 W. L. JONES, JR. ETAL DUPLEX CAPSTAN 5 Sheets-Sheet 1 INVENTORS W/LBERT L. J0/VE$,JR. CHESTER L. BUCHANAN JERV/S' J. GEN/VAR/ ATTORNEYS J1me 1966 w. L. JONES, JR., ETAL 3,258,247

DUPLEX CAPSTAN Filed Dec. 51, 1965 5 Sheets-Sheet 2 INVENTOR. W/LBERT L. JONES, JR CHESTER L. BUCHANAN JERV/S J GENNAR/ BY a firs Z4 ATTORNEY,

J1me 1966 w. L. JONES, JR., ETAL 3,253,247

DUPLEX CAP S TAN 5 Sheets-Sheet 3 Filed Dec. 51, 1965 FIG 4A INVENTORS W/LBERT L. JONES, JR CHESTER L. BUCHANAN JERV/S J. GE/VA/AR/ ATTORNEYS United States Patent 3,258,247 DUPLEX CAPSTAN Wilbert L. Jones, Jr., Chester L. Buchanan, and Jervis J.

Gennari, Washington, D.C., assignors to the United States of America as represented by the Secretary of the Navy Filed Dec. 31, 1963, Ser. No. 334348 Claims. (Cl. 254150) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to heavy-load-capacity hoists and more particularly to a hauling capstan for use in a two unit hauling and storage type hoist system.

In the field of underwater technology there has been an increasing demand for improved high-load-capacity deep-sea hoist equipment. Peculiar to this type of hoist equipment is the requirement for not only hoisting heavy loads but also in conjunction with said hoisting, storing the long lengths of cable involved. When a long cable supporting a heavy load is wound directly onto a single drum in a multitude of layers, the shear loads exerted against the side flanges as well as the compressive loads about the drum shell become exceedingly high. This problem has been alleviated to some degree by employing two separate units, one for accomplishing the hauling function and the other for storing the cable at greatly reduced tension. 7

In utilizing a hoist system of the two unit type it is necessary that the capstan or hoisting unit provides continuous cable hauling which is free of slippage and side play and also laterally advances the cable as the hoist drum rotates. It is further desirous to avoid contact between adjacent turns of cable in order to extend cable life. In the past, attempts have been made to solve this problem by employing a pair of axially aligned grooved drums to provide for the continuous hauling and lateral advancement of the cable. Grooved drums only slightly reduce the cable wear caused by contacting turns in that approximately 180 of cable circumference is contacted by the drum and the compressive force between the drum shafts is of such a magnitude that massive structural support is required, adding measurably to the weight support and space requirements which have already been made excessive by the use of a pair of axially-spaced drums.

The duplex capstan of the present invention provides both; for a continuous hauling capability, as well as for the lateral advancement of cable along the drum with a substantial reduction in size and weight requirements for hoisting equivalent loads and cable lengths.

The duplex capstan of the present invention essentially comprises a pair of simultaneously-driven axially-slotted cylinders with their bars intermeshed such that they rotate through substantially the same space on axes which are offset and canted with respect to each other. Through this construction, a cable wound about the capstan will contact only one of the cylinders for half of the circumference of the capstan while also being laterally advanced therealong.

An object of the present invention is to provide a compact, heavy-load, cable hoisting unit.

Another object of the present invention is the provision of a capstan which will provide continuous cable hauling free from slippage and sideplay.

A further object of this invention is to provide a capstan which will laterally advance a cable therealong Without contact between succeeding cable turns.

Yet another object of the present invention is the provision of a capstan whichwill laterally advance a cable therealong with a minimum of cable-capstan contact.

These and other objects as well as many of the attendant advantages of this invention will become readily apparent and at the same time become better understood by reference to the following detailed description when the same is considered in conjunction'with the accompanying drawings wherein:

FIG. 1 is a diagrammatic view of a two unit cable hauling and storage system.

FIG. 2 is a perspective view of the novel capstan of the present invention.

FIG, 3 is a section view taken along the line 33 of FIG. 2.

FIGS. 4A and 4B are schematic views showing the path of an element of cable during one rotation of the capstan.

FIG. 5 is a sectional view of a small segment of the cable carrying surfaces of the capstan.

Referring now in detail to the drawings, wherein like reference characters represent like parts throughout the several views, there is shown in FIG. 1 a typical two unit hoist system, mounted on a research vessel, generally designated 10. The two unit system basically comprises a cable storage unit 12 mounted below deck, a cable hauling unit 14, mounted on a machinery platform 16 over a receiving well 18.

The capstan of the present invention is employed as a hauling unit 14 and comprises a pair of upright support members 29 capable of being secured to a machinery platform 16 by means of bolts 22 or similarly. A cylindrical shaft 24 is fixedly secured between the upper ends of support members 29. In the illustrated embodiment of FIGS. 2 and 3 the shaftl24 extends through apertures in the supports 26 and is secured therein by a pair of seated cap screws 26.

A pair of intermeshed squirrel-cage-like drums 30 and 40 are mounted for rotation about shaft 24. The drums are both canted and offset with respect to each other by means of eccentric journals which are keyed to the shaft 24 by an elongated key 28. Drum 30 includes a first side disc 32 including an internal annular face 31 of Teflon or preferably machined brass, mounted for rotation about journal 33 and a second side disc 34 having a similar annular bearing face 31 mounted for rotation about journal 35. A plurality of cross bars 36 are mounted between discs 32 and 34 at their peripheries by recessed cap screws 38.

A similar pair of support discs 42 and 44 having internal annular bearing faces 31 are mounted for rotation about eccentric journals 43 and 45 respectively. The journals 35 and 45 are exact duplicates as are journals 33 and 43. A plurality of cross bars 46 are similarly mounted between discs 42 and 44 at their peripheries by recessed cap screws 38. It will be appreciated from FIG. 2 that discs 34 and 44 are of lesser radius than discs 32 and 42 and that bars 36 and 46 are attached directly to the peripheral edge of discs 34 and 44 while beingseated in recesses in discs 32 and 42.

Driving means are attached to each of the outer discs 32 and 42 although a single drive means could well be attached to only one of the discs permitting the intermesh of the respective bar members to provide the drive for the other drum. Such single drive means however would result in less efficiency and greater wear and it is prefer able to apply an equal torque to both drums. The torque transmission may be provided by gearing, roller chains or any similar drive means. In the illustrated embodiment a pair of steel plate sprockets 50 are secured, one each, to end discs 32 and 42 by a plurality of cap screws 52. The sprockets 50 are spaced from discs 32 and 42 by spacers 54 and are interiorly spaced from spacers 56 at 58.

A plurality of spacers 56, 60, 62 and 64 are employed to maintain a specified distance between journals 43, 35,

45 and 33 as well as to laterally secure the relationship between rotary drums 30 and 40 and the support members 20. Each of the spacers 56, 60, 62 and 64 are also keyed to shaft 24 by means of key 28.

In operation, the offset relation of the slotted drum causes the cable which is wound about the capstan to be carried for half the circumference of the capstan by the bar members of each drum. For each half revolution of the capstan, the bar members of one drum carry the cable. During the other half of the revolution of the capstan, the bar members of the other drum carry the cable. Thus, as the capstan rotates, an elementof the cable is transferred from the bar members of one drum to those of the other, every 180 degrees. The canted relation of the bars causes the cable to advance laterally across the capstan.

The result of these operations is to advance the cable laterally across the capstan in a series of approximately helical turns. The pitch of the helix is determined by the angle between the canted axes of the drums.

The operating principle of the canted drums is best shown in FIGS. 4A and 4B. The drums are shown both canted and offset with respect to each other. Assume that the cable is movingfrom right to left. The cable first makes contact at point a, which is on a bar of the upper drum (as seen in the sectional view). This drum is canted in such a'direction that it pulls the cable laterally toward the other drum. As the cable leaves the upper drum" and passes across the gap between the drums at right angles to the axis of rotation (point (d)), it is transferred to the lower drum because the bar members of the lower drum now pass outside of the periphery of the upper drum. The lower drum will carry the cable during the next half revolution. Since the drum is canted, it causes the cable to traveljlaterally in the same direction and at the same rate as before. After passing the horizontal axis (point 1') the upper drum engages the cable and continues moving it laterally as it rotates (points 1' to m). Neglecting relaxation, the cable motion is purely rolling action, free of slippage and sideplay. There are no unbalanced forces to cause this path to be altered. Each element of cable follows the preceding element throughout the same path.

This cable advancing process is reversible. Assuming the cable to be moving from left to right (FIG. 4a), it

- first makes contact at point m, which is located on a bar of the upper drum. As the drum rotates clockwise, the cable is pulled laterally toward the other drum, since the upper drum is canted in the same direction. As the cable passes the horizontal plane (point j), parallel to the axis of rotation, it is transferred to the lower drum because the bar members of the lower drum are now passing to the outside of the upper drum. As before, the cable is displaced laterally due to the canted relation of the drums. After being pulled through one-half revolution on the lower drum, the cable is transferred to the upper drum which engages the cable and moves it laterally until the cable leaves the drumat point a. The reversibility of the process is an important requirement for hoisting applications. For proper operation of this capstan, the cable must be guided to the capstan in a path which is perpendicular to the axis of rotation of the drum it initially contacts. Any suitable guide mechanism such as fixed-position, opposed-rollers, for example, would be sufficient.

The lateral displacement of the cable is directly proportional to the angle to which the drum members are canted. For the purpose of illustration, the cant angle is exaggerated in order to' better portray the cable path across the drum. In actual practice however, this angle may be quite small. As an example, let us assume that a length of l-inch-diameter cable is wound around a 48- inch-diameter capstan, as shown in FIG. 4a. The minimum lateral displacement must be at least one cable diameter per revolution of the capstan. Then in a half 4 turn of the capstan, the cable must advance a half cable diameter or /2 inch.

Since the other drum must also be canted to laterally displace the cable druing the other half revolution, the total cant angle =2a=l12'.

The offset must lie in a plane which is perpendicular to the plane in which the drums are can-ted, and it must be of suff cient magnitude to cause each drum member to engage the cable for only a half revolution. The minimum amount of offset required is equal to the prodnot of the drum radius and the versine of half the angle subtended by the gap between the bars of one drum (this minimum is required to maintain clearance between the cable and the bars of the drum which are not to be contacted). Both the offset and cant angle limit the cross-sectional contours of the bars, since they obviously must be shaped to operate intermeshed, but free from mutual interference.

To obtain the desired action between drum members, eccentric journals, whose bearing faces are both offset and canted with respect to the mounting shaft, are employed. FIG. 3 shows the arrangement of the journals 43, 45, 33 and 35.

It is due to this arrangement of eccentric journals that both ends of the cross bars can be supported and accordingly the aforementioned cable-advancing princple may be applied to a high-load capacity capstan. Heretofore, reels based on this principle were of the fingered cantilever drum design. The inherent weakness of the cantilever design limits their us to low-tension winding applications, such as are found in the textile industry. However, in the capstan of the present invention the drums are much stronger because the bar members are rigidly supported at both ends.

The peripheral contour of the bar members also must be considered. It has been observed that considerable wear results from action between the cable and the contact surfaces of the bar members when they are curved to the drum radius. The wear is due to the sharp bending of the cable across the unsupported gap between the bars. This difiiculty becomes negligible if the bars are shaped to provide a smooth transition from the radius of the drum to the chord between the bars. The correction may be determined by the ratio S/S'=R/r Algebraic rearrangement gives the correction radius r necessary for smooth transition as shown in FIG. 5.

T SR S As can be seen from the foregoing the capstan of the present invention provides a compact yet sturdy cable pulling unit which willprovide for continuous hauling without sideplay or slippage while also providing for the lateral advancement of the cable being hoisted in a manner which substantially eliminates conditions critical to cable wear.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

l. A heavy duty hauling capstan for continuously hauling long lengths of subsequently stored cable comprising:

a pair of upright support members,

a rIiDgid shaft fixedly secured between said support memers,

first, second, third and fourth eccentric journals eccentrically mounted on said shaft along the axis thereof and secured against rotation,

first, second, third and fourth disc members mounted for rotation eccentrically about said first, second, third and fourth journals respectively,

a plurality of cross bars, half of said cross bars being mounted at their ends between the peripheral edges of said first and third disc members and the other half being mounted at their ends between the peripheral edges of said second and fourth disc members to form a pair of intermeshed axially slotted rotary drums, and

means connected to each of said drums for imparting rotary motion thereto.

2. A heavy'duty hauling capstan according to claim 1 wherein said first journal is identical in structure to said fourth journal and said second journal is identical in structure to said third journal.

3. A heavy duty hauling capstan according to claim 1, wherein said eccentrically mounted journals cause said cross bars of one of said drums to be both canted and axially offset with respect to the cross bars of the other of said drums.

4. A heavy duty hauling capstan for continuously hauling long lengths of subsequently stored cable comprising: I

upright support members and a rigid shaft fixedly secured between said support members,

first, second, third and fourth eccentric journals mounted on said shaft,

first, second, third and fourth disc members mounted for rotation eccentrically about said first, second, third and fourth journals respectively,

a plurality of cross bars, half of said cross bars being mounted at their ends between the peripheral edges of said first and third disc members and the other half mounted at their ends between the peripheral edges of said second and fourth disc members to form a bridge-like support structure, and

means connected to said first and fourth disc for imparting rotary motion thereto.

5. A heavy duty hauling capstan according-to claim 4, wherein said eccentrically mounted journals cause said cross bars of one of said drums to be both canted and axially offset with respect to the cross bars of the other of said drums.

References Cited by the Examiner UNITED STATES PATENTS 2,628,411 2/1953 McLellan 242-4705 2,656,584 10/1953 Nelson 242-4705 EVON C. BLUNK, Primary Examiner.

SAMUEL F. COLEMAN, Examiner.

H. HORNSBY, Assistant Examiner. 

1. A HEAVY DUTY HAULING CAPSTAN FOR CONTINUOUSLY HAULING LONG LENGHTS OF SUBSEQUENTLY STORED CABLE COMPRISING: A PAIR OF UPRIGHT SUPPORT MEMBERS, A RIGID SHAFT FIXEDLY SECURED BETWEEN SAID SUPPORT MEMBERS, FIRST, SECOND, THIRD AND FOURTH ECCENTRIC JOURNALS ECCENTRICALLY MOUNTED ON SAID SHAFT ALONG THE AXIS THEREOF AND SECURED AGAINST ROTATION, FIRST, SECOND, THIRD AND FOURTH DISC MEMBERS MOUNTED FOR ROTATION ECCENTRICALLY ABOUT SAID FIRST, SECOND, THIRD AND FOURTH JOURNALS RESPECTIVELY, A PLURALITY OF CROSS BARS, HALF OF SAID CROSS BARS BEING MOUNTED AT THEIR ENDS BETWEEN THE PERIPHERAL EDGES 